diff --git a/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.C b/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.C
index c1134f44e1..030090d3d5 100644
--- a/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.C
+++ b/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.C
@@ -35,7 +35,7 @@ bool Foam::OTstream::write(const token& tok)
 {
     if (tok.good())
     {
-        append(tok);
+        tokens().push_back(tok);
         return true;
     }
 
@@ -48,7 +48,7 @@ Foam::Ostream& Foam::OTstream::write(const char c)
     if (!std::isspace(c) && std::isprint(c))
     {
         // Should generally work, but need to verify corner cases
-        append(token(token::punctuationToken(c)));
+        tokens().push_back(token(token::punctuationToken(c)));
     }
 
     return *this;
@@ -76,7 +76,7 @@ Foam::Ostream& Foam::OTstream::write(const char* str)
 
 Foam::Ostream& Foam::OTstream::write(const word& str)
 {
-    append(token(str)); // tokenType::WORD
+    tokens().push_back(token(str)); // tokenType::WORD
 
     return *this;
 }
@@ -84,7 +84,7 @@ Foam::Ostream& Foam::OTstream::write(const word& str)
 
 Foam::Ostream& Foam::OTstream::write(const string& str)
 {
-    append(token(str)); // tokenType::STRING
+    tokens().push_back(token(str)); // tokenType::STRING
 
     return *this;
 }
@@ -98,11 +98,11 @@ Foam::Ostream& Foam::OTstream::writeQuoted
 {
     if (quoted)
     {
-        append(token(string(str))); // tokenType::STRING
+        tokens().push_back(token(string(str))); // tokenType::STRING
     }
     else if (!str.empty())
     {
-        append(token(word(str, false))); // tokenType::WORD
+        tokens().push_back(token(word(str, false))); // tokenType::WORD
     }
 
     return *this;
@@ -111,7 +111,7 @@ Foam::Ostream& Foam::OTstream::writeQuoted
 
 Foam::Ostream& Foam::OTstream::write(const int32_t val)
 {
-    append(token(label(val))); // tokenType::LABEL
+    tokens().push_back(token(label(val))); // tokenType::LABEL
 
     return *this;
 }
@@ -119,7 +119,7 @@ Foam::Ostream& Foam::OTstream::write(const int32_t val)
 
 Foam::Ostream& Foam::OTstream::write(const int64_t val)
 {
-    append(token(label(val))); // tokenType::LABEL
+    tokens().push_back(token(label(val))); // tokenType::LABEL
 
     return *this;
 }
@@ -127,7 +127,7 @@ Foam::Ostream& Foam::OTstream::write(const int64_t val)
 
 Foam::Ostream& Foam::OTstream::write(const float val)
 {
-    append(token(val)); // tokenType::FLOAT
+    tokens().push_back(token(val)); // tokenType::FLOAT
 
     return *this;
 }
@@ -135,7 +135,7 @@ Foam::Ostream& Foam::OTstream::write(const float val)
 
 Foam::Ostream& Foam::OTstream::write(const double val)
 {
-    append(token(val)); // tokenType::DOUBLE
+    tokens().push_back(token(val)); // tokenType::DOUBLE
 
     return *this;
 }
diff --git a/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.H b/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.H
index 856ba2eab4..bd6076c043 100644
--- a/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.H
+++ b/src/OpenFOAM/db/IOstreams/Tstreams/OTstream.H
@@ -101,13 +101,13 @@ public:
     // Member Functions
 
         //- The tokens
-        const DynamicList<token>& tokens() const
+        const DynamicList<token>& tokens() const noexcept
         {
             return *this;
         }
 
         //- The tokens
-        DynamicList<token>& tokens()
+        DynamicList<token>& tokens() noexcept
         {
             return *this;
         }
diff --git a/src/OpenFOAM/meshes/bandCompression/bandCompression.C b/src/OpenFOAM/meshes/bandCompression/bandCompression.C
index 428421d4c0..ffcb574f48 100644
--- a/src/OpenFOAM/meshes/bandCompression/bandCompression.C
+++ b/src/OpenFOAM/meshes/bandCompression/bandCompression.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -137,8 +137,8 @@ Foam::labelList cuthill_mckee_algorithm
                     if (unvisited.test(nbr))
                     {
                         // Not visited (or removed), add to the list
-                        nbrCells.append(nbr);
-                        weights.append(nbrCount);
+                        nbrCells.push_back(nbr);
+                        weights.push_back(nbrCount);
                     }
                 }
 
@@ -284,8 +284,8 @@ Foam::labelList Foam::meshTools::bandCompression
                     if (unvisited.test(nbr))
                     {
                         // Not visited (or removed), add to the list
-                        nbrCells.append(nbr);
-                        weights.append(nbrCount);
+                        nbrCells.push_back(nbr);
+                        weights.push_back(nbrCount);
                     }
                 }
 
diff --git a/src/OpenFOAM/primitives/strings/lists/SubStrings.H b/src/OpenFOAM/primitives/strings/lists/SubStrings.H
index 79d38b947e..8279d2d10d 100644
--- a/src/OpenFOAM/primitives/strings/lists/SubStrings.H
+++ b/src/OpenFOAM/primitives/strings/lists/SubStrings.H
@@ -32,8 +32,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef SubStrings_H
-#define SubStrings_H
+#ifndef Foam_SubStrings_H
+#define Foam_SubStrings_H
 
 #include <regex>  // For std::sub_match
 #include <string>
@@ -88,6 +88,12 @@ public:
             return len;
         }
 
+        //- Retrieve element at pos, converted to a string type.
+        StringType str(size_t pos) const
+        {
+            return (*this)[pos].str();
+        }
+
         //- Append sub-string defined by begin/end iterators
         void append
         (
@@ -116,12 +122,6 @@ public:
         {
             return this->back();
         }
-
-        //- Get element at pos, converted to a string type.
-        StringType str(size_t pos) const
-        {
-            return (*this)[pos].str();
-        }
 };
 
 
diff --git a/src/meshTools/polyTopoChange/polyTopoChange.C b/src/meshTools/polyTopoChange/polyTopoChange.C
index a2558d09ad..60b0cc76a9 100644
--- a/src/meshTools/polyTopoChange/polyTopoChange.C
+++ b/src/meshTools/polyTopoChange/polyTopoChange.C
@@ -687,8 +687,8 @@ Foam::label Foam::polyTopoChange::getCellOrder
                     if (unvisited.test(nbr))
                     {
                         // Not visited (or removed), add to the list
-                        nbrCells.append(nbr);
-                        weights.append(nbrCount);
+                        nbrCells.push_back(nbr);
+                        weights.push_back(nbrCount);
                     }
                 }